I love my Asus Zenwatch and use it all the time.
The best use case: My phone (Nexus 6) rings in my pocket. It buzzes my wrist and I look at the watch. I see a picture of the caller and their name. I can swipe left (answer) or right (voicemail).
This simple interaction is so much more pleasant than taking out my phone to do the same thing. It doesn’t save THAT much time, but it is much more usable and elegant.
Second, it is stylish. I like the way it looks. It’s got swag. It’s not thick like the moto 360 and not smallish like the iWatch.
The operating system works well and shows me relevant information.
The watch face (after messing with a dozen different ones) I settled on is called Street Art. It looks great and has different art every 30 minutes or so.
I strongly recommend it if you use a Android phone.